This might expose me as a noob, but seems like it would be easier to just setup up your phone as a hotspot using joikuspot or hotspot. Just have your router see it as such, and pair it that way.

As I think you might have some bandwidth limitations this way that you'll never even reach as 3g wont push that kind of data through.

I'm fairly certian Tomato shoudl allow that. Just make sure you're gateway settings are right, and you have the router set to the right mode. Then you could use the USB for charging only (via the charger itself as that would be optimal).

The only downside is I'm not sure what this woudl do to the life of your phone. Running it as a router essentially tends to get mine pretty hot. I'd imagine eventually you'd kill it, but can only speculate.

2d